Solvation properties of non-polar amino acids in water and methanol: a molecular dynamics study

Abstract

Solvation properties of the amino acids alanine, valine, leucine and phenylalanine in water and in methanol at infinite dilution have been studied by using molecular dynamics simulations. The free energy transfer of the solutes from water to methanol has been calculated by means of a slow-growth technique and the results compared with diverse hydrophobicity scales available in the literature. Chothia's linear relation between the accessible surface area and the hydrophobicity is shown. The line obtained has a slope equivalent to 49cal mol−1 Å−2. The radial distribution of solvent molecules around the amino acids residues is considered, and a comparison is made of the number of hydrogen bonds formed between water molecules in the presence and in the absence, respectively, of the amino acids. The calculations show clearly that the solvation structure near the non-polar amino acids is richer for methanol than for water.